This invention relates generally to a bridge construction technique for a cable stayed segmental bridge in which modules in the form of precast concrete, hollow box girders are progressively placed and interconnected to form both a relatively long main bridge span as well as approach bridge spans at opposite ends of the main span which is constructed as a continuation of the approach spans utilizing essentially the same box girders and avoiding the need for specialized construction equipment.
Various methods have been employed in the past for constructing the relatively short approach spans and the relatively long main span or spans which normally require special equipment and various kinds of deck sections for these different spans. For segmental bridge construction from concrete box girders, the shorter approach spans are oftentimes constructed using a cantilever technique whereby the segments are cantilevered and interconnected, one to the other, in opposite directions starting from a given bridge pier. A disadvantage with such technique is that, not only are costly and heavy equipment required for the job, but instability during construction creates serious problems as care must be taken to avoid uneven loading of the bridge segments on opposite sides of the pier, torsional instability from gusting winds when erecting long cantilevered spans, etc. Also, the length of the main span over a large body of water or a ravine is limited by such a method which requires the costly installation of piers in the water body or deep ravine. Nevertheless, the cantilever method is useful over some of the other bridge construction approaches requiring heavy equipment floated on the water, which presents many other drawbacks in logistics and only adds to the time and cost involved in constructing the bridge.
Cable stayed segmental bridges of concrete box girders permit longer main spans but oftentimes require different deck sections and special bridge equipment compared to that employed for the approach spans. Besides, main deck suspension by cable stays successively connected to high bridge pylons required for the main span or spans, can be quite time consuming and costly, and two-wide box girder bridges may require twin pylons and associated cables thereby adding to the time and cost of construction.